<template>
  <div id="app">
    <transition :name="transition">
      <router-view/>
    </transition>
    </div>
</template>

<script>
export default {
  name: 'App',
  data() {
    return { transition: '' };
  },
  watch: { // 使用watch 监听$router的变化
    $route(to, from) {
      // 如果to索引大于from索引,判断为前进状态,反之则为后退状态
      if (to.meta.index > from.meta.index) {
        // 设置动画名称
        this.transition = 'slide-left';
      } else {
        this.transition = 'slide-right';
      }
    },
  },
};
</script>
<style>
* {
  padding: 0;
  margin: 0;
}
.slide-right-enter-active,
.slide-right-leave-active,
.slide-left-enter-active,
.slide-left-leave-active {
  will-change: transform;
  transition: all 500ms;
  position: absolute;
}
.slide-right-enter {
  opacity: 0;
  transform: translate3d(-100%, 0, 0);
}
.slide-right-leave-active {
  opacity: 0;
  transform: translate3d(100%, 0, 0);
}
.slide-left-enter {
  opacity: 0;
  transform: translate3d(100%, 0, 0);
}
.slide-left-leave-active {
  opacity: 0;
  transform: translate3d(-100%, 0, 0);
}
</style>
